985 resultados para neurofunctional reorganization


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Changes in intermediate and deep ocean circulation likely played a significant role in global carbon cycling and meridional heat/moisture transport during the middle Miocene climate transition (~14 Ma). High-resolution middle Miocene (16-13 Ma) benthic foraminifer stable isotope records from the South China Sea reveal a reorganization of regional bottom waters, which preceded the globally recognized middle Miocene ~1 per mil d18O increase (13.8 Ma) by 100,000 years. An observed reversal of the benthic foraminifera d13C gradient between ODP Sites 1146 (2092 m) and 1148 (3294 m; 13.9-13.5 Ma) is interpreted to reflect an increase in the southward flux of low d13C deep (> 2000 m) Pacific Ocean waters (Flower and Kennett, 1993, doi:10.1029/93PA02196; Shevenell and Kennett, 2004). Large-scale changes in Pacific intermediate and deep ocean circulation, coupled with enhanced global carbon cycling at the end of the Monterey Carbon Isotope excursion, likely acted as internal feedbacks to the Earth's climate system. These feedbacks reduced the sensitivity of Antarctica to lower latitude-derived heat/moisture and facilitated the transition of the Earth's climate system to a new, relatively stable glacial state.

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An investigation of stable isotope (d13C TOC and d15N TN) and elemental parameters (TOC, TN contents and TOC/TN ratios) of bulk organic matter (<200 µm) from sediment cores recovered from the Patagonian lake Laguna Potrok Aike (Argentina) in the framework of the ICDP deep drilling project PASADO provided insights into past changes in lake primary productivity and environmental conditions in South Patagonia throughout the last Glacial-Interglacial transition. Stratigraphically constrained cluster analyses of all proxy parameters suggest four main phases. From ca 26,100 to 17,300 cal. years BP, lacustrine phytoplankton was presumably the predominant organic matter source in an aquatic environment with low primary productivity rates. At around 17,300 cal. years BP, abrupt and distinct shifts of isotopic and elemental values indicate that the lacustrine system underwent a rapid reorganization. Lake primary productivity (phytoplankton and aquatic macrophytes) shows higher levels albeit with large variations during most of the deglaciation until 13,000 cal. years BP. The main causes for this development can be seen in improved growing conditions for primary producers because of deglacial warming in combination with expedient availability of nutrients and likely calm wind conditions. After 13,000 cal. years BP, decreased d13C TOC values, TOC, TN contents and TOC/TN ratios indicate that the lake approached a new state with reduced primary productivity probably induced by unfavourable growing conditions for primary producers like strengthened winds and reduced nutrient availability. The steady increase in d15N TN values presumably suggests limitation of nitrate supply for growth of primary producers resulting from a nutrient shortage after the preceding phase with high productivity. Nitrate limitation and consequent decreased lacustrine primary productivity continued into the early Holocene (10,970-8400 cal. years BP) as reflected by isotopic and elemental values.

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We use a suite of eight ocean biogeochemical/ecological general circulation models from the MAREMIP and CMIP5 archives to explore the relative roles of changes in winds (positive trend of Southern Annular Mode, SAM) and in warming- and freshening-driven trends of upper ocean stratification in altering export production and CO2 uptake in the Southern Ocean at the end of the 21st century. The investigated models simulate a broad range of responses to climate change, with no agreement ona dominance of either the SAM or the warming signal south of 44° S. In the southernmost zone, i.e., south of 58° S, they concur on an increase of biological export production, while between 44 and 58° S the models lack consensus on the sign of change in export. Yet, in both regions, the models show an enhanced CO2 uptake during spring and summer. This is due to a larger CO 2 (aq) drawdown by the same amount of summer export production at a higher Revelle factor at the end of the 21st century. This strongly increases the importance of the biological carbon pump in the entire Southern Ocean. In the temperate zone, between 30 and 44° S all models show a predominance of the warming signal and a nutrient-driven reduction of export production. As a consequence, the share of the regions south of 44° S to the total uptake of the Southern Ocean south of 30° S is projected to increase at the end of the 21st century from 47 to 66% with a commensurable decrease to the north. Despite this major reorganization of the meridional distribution of the major regions of uptake, the total uptake increases largely in line with the rising atmospheric CO2. Simulations with the MITgcm-REcoM2 model show that this is mostly driven by the strong increase of atmospheric CO2, with the climate-driven changes of natural CO2 exchange offsetting that trend only to a limited degree (~10%) and with negligible impact of climate effects on anthropogenic CO2 uptake when integrated over a full annual cycle south of 30° S.

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High-resolution planktonic foraminiferal census data from Santa Barbara Basin (Ocean Drilling Program hole 893A) demonstrate major assemblage switches between 25 and 60 ka that were associated with Dansgaard-Oeschger cycles. Stadials dominated by Neogloboquadrina pachyderma (sinistral), and Globigerinoides glutinata suggest a strong subpolar California Current influence, while interstadials marked by abundant N. pachyderma (dextral) and G. bulloides indicate a relative increase in subtropical countercurrent influence. Modern analog technique and transfer function (F-20RSC) temperature reconstructions support d18O evidence of large rapid (70 years or less) sea surface temperature shifts (3° to 5°C) between stadials and interstadials. Changes in the vertical temperature gradient and water column structure (thermocline depth) are recorded by planktonic faunal oscillations suggest bimodal stability in the organization of North Pacific surface ocean circulation. Santa Barbara Basin surface water demonstrates the rapid response of the California Current System to reorganization of North Pacific atmospheric circulation during rapid climate change.

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Issues for 1832-1933, v. 26-63 called also ser. 2, v. 1-38.

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Description based on : 2006/2007 ; title from cover.

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Mode of access: Internet.

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"During the 1996 spring session, the General Assembly passed and the Governor signed landmark legislation creating a Department of Human Services (DHS) effective July 1, 1997. The new department consolidates three human services departments in their entirety : Department of Alcoholism and Substance Abuse (DASA) - Department of Rehabilitation Services (DORS) - Department of Mental Health and Developmental Disabilities (DMH/DD)."

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Submission of an annual report by the Dept. of state was provided for in the reorganization of state departments effective Jan. 1, 1927. Prior to that date there were only a few reports issued in printed form.

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Nos. 1-56, July 26, 1913-Aug. 15, 1914, were issued weekly in the form of leaflets; no. 57-92, Jan. 1915-Dec. 1917, monthly, in the form of pamphlets, containing studies in government; no. 93-95, irregularly issued.

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The Committee was charged with making a study of the report of the Iowa Governmental Reorganization Commission of 1950 and to make such other investigations and recommendations as it deemed pertinent.

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Pt. 2 has subtitle: "Session on S. 3897, a bill to improve governmental budgeting and accounting methods and procedures."

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Pt. 5 issued by the subcommittee under its later name: Subcommittee on Reorganization, Research, and International Organizations.